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Hello!
Other than 7815, what else the Philips CD104 uses in the power supply as regulator purpose?
I want to upgrade those regulators to Dexa replacements.
Many thanks!
Follow Ups:
Tube747
post some pics of your project!
Hi,
The service manual is on-line and you can easily find it.
I am unsure changing the regulator chips is the biggest win in this CDP (and others of similar vintage).
A kep problem is the Digital Filter which creates truly massive amounts of noise on many power supplies, at frequencies that regulates are not effective.
Another problem is an inadequate design of the analogue stage, which exposes a "slow" op-amp to very fast edge rates - a recipe for creating transient intermodulation.
This sort of problem can be resolved by changing the circuit or using faster speed Op-Amp's.
I suspect replacing all electrolytic capacitors (they will have aged well past their useful life), cleaning up the power supplies connected to the Digital Filter using suitable means (in my books a few kuF of Os-Cons and serious Chokes) plus using better suited Op-Amp's (or other circuitry - just check old Audio Amateur etc. issues covering mods to these CDP's) will produce a much better CDP than using fancy regulators and clocks, without fixing fundamental issues.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
Hi Thorsten,
I have a Mission working DAD7000, which sounds smooth but very veiled to me, compared to my modest NAD C525 BEE and various Sony ES machines from the 90's in my collection. When I changed the belt so that the door would work, I was impressed at how well built this player is. It had occurred to me that a replacement of the electrolytic capacitors could really help. After all, the reputation is that this player should sound good. I am also suspicious of the mysterious box that mission put before the output jack, that I suspect is there to smooth the sound, but could be adding some veiling.
Lampizator suggests Burr Brown OPA2604 for the Op-Amp. Do you thing that it would be suitable?
Dave
Hi,
Never worked on a Mission, but not many comments here, but a full recap does tend to help a lot on older gear. Full Recap here meaning replacing each and every electrolytic cap in sight with modern alternatives.
I would not use the OPA2604 these days. But I really don't want to get into "Op-Amp du jour" debates. I still think the correct choice for CDP are low noise, high speed Video Op-Amp's.
Ciao T
At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to untolerable pain. Really, what more could we need?
Keep me posted and your project -Crazy Dave
Worst case scenario it will be great solder practice!
Dave
We need more "modders" cd players- Dave.
Have fun!
Will do!
Dave
An example (caps, op-amps)
The Well Tempered Computer
The unit has some 1500uf and 3300uf capcitor in the power supply, do you think I can replace those caps with BHC T-network (4 poles) caps?
Thanks!
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